In 3GPP (3rd Generation Partnership Project), which is a project aiming to standardize a mobile communication system, a discontinuous reception (DRX) is prescribed as a discontinuous reception technique to reduce power consumption of a radio terminal. A radio terminal executing a DRX operation in an idle mode discontinuously monitors a downlink control channel for receiving a paging message. A cycle for monitoring the downlink control channel is referred to as “DRX cycle”.
In recent years, machine-type communication (MTC) in which a radio terminal performs communication without human intervention in a mobile communication system has attracted attention. From such a background, an ongoing discussion is a new introduction of an extended DRX cycle longer than a conventional DRX cycle to further reduce power consumption (for example, see Non Patent Document 1). The DRX using the extended DRX cycle is referred to as “extended DRX”.